Embodiments of the present disclosure are directed to an image processing apparatus and an image processing method.
By applying a linear filter to extract a contour of an image from an input image signal, and adding (or subtracting) the result obtained by applying the linear filter to the input image signal as a gain, it is possible to enhance the sharpness of the contour of an image and thus sharpen an image. An output image provided as a result of this sharpening operation is a sharper image than the input image represented by the input image signal by increasing the change of the pixel values of a contour having a local varying gray scale.
However, when a sharpening calculation is performed only by a linear operation as described above, the change of the pixel values may affect other pixel values, such as pixel values of a pixel adjacent to a contour pixel. Therefore, when the sharpening calculation is performed only by a linear operation as described above, there is a possibility that an overshoot or undershoot occurs. Also, when an overshoot or undershoot occurs, the output image quality decreases.
Technology that inhibits the overshoot or undershoot has been developed. When the overshoot or undershoot is inhibited at the peak of, such as a thin line or dot in an image to be processed, the output image may not have sufficient sharpness. Therefore, to improve image quality, an overshoot or undershoot may occur based on an input image signal. However, conventional technologies have limits in processing an image to improve image quality.